Filling schemes of silver dots inkjet-printed on pixelated nanostructured surfaces

Abstract

Recently, our group demonstrated an inkjet-based technique to enable high-throughput, versatile and full-colour printing of structural colours on generic pixelated nanostructures, termed as molded ink on nanostructured surfaces. The printed colours are controlled by the area of printed silver on the pixelated red, green and blue polymer nanostructure arrays. This paper investigates the behaviour of jetted silver ink droplets on nanostructured surfaces and the microscale dot patterns implemented during printing process, for achieving accurate and consistent colours in the printed images. The surface wettability and the schemes of filling silver dots inside the subpixels are crucial to the quality of printed images. Several related concepts and definitions are introduced, such as filling ratio, full dots per subpixel (DPSP), number of printable colours, colour leaking and dot merging. In our experiments, we first chemically modified the surface to control the wettability and dot size. From each type of modified surface, various filling schemes were experimented and the printed results were evaluated with comprehensive considerations on the number of printable colours and the negative effects of colour leaking and dot merging. Rational selection of the best filling scheme resulted in a 2-line filling scheme using 20 μm dot spacing and line spacing capable of printing 9261 different colours with 121 pixel per inch display resolution, on low-wettability surface. This study is of vital importance for scaling up the printing technique in industrial applications and provides meaningful insights for inkjet-printing on nanostructures.

Scalable Inkjet-Based Structural Color Printing by Molding Transparent Gratings on Multilayer Nanostructured Surfaces

“…As determined from digital image processing, when printed at full ink density, the actual filling ratio on the red, green, and blue grating surface is about 29%, 40%, and 39%, respectively. As studied in our previous work, dot merging can cause randomness in the filling ratio and thus affects the accuracy of the pixel brightness . When printed with denser ink droplets, the negative effect of merging is more pronounced.…”

“…Recent years have witnessed tremendous progress in generating colors from artificial nanostructures, a field known as structural color printing. Various structural coloration mechanisms based on interaction of light with optical nanostructures have been intensively studied and demonstrated, for example, plasmonic colors from metal nanostructures, − colors originating from optical resonances in dielectric metasurfaces, − reflective colors from photonic crystals, − diffractive colors from nanostructure arrays, − and interference colors in thin films. − Compared to conventional coloration approaches based on dyes or pigments, structural color printing has appealing advantages: structural colors can be patterned in ultrahigh resolution, with the smallest pixels in subwavelength scale; , structural color printing usually implements metals and dielectric materials that are environmentally friendly; since the colors are generated from physical structures, structural colors are usually very resistant to fading. , …”

“…The same type of ink was also inkjet-printed into optical-grade thin films to generate thickness-dependent interference colors for custom-input images . Our previous work has introduced an inkjet-based molded-ink-on-nanostructured-surface (MIONS) printing, which implements a nanostructured surface composed of pixelated nanocone arrays for printing full-color images. , Silver nanoparticle ink droplets were accurately printed onto red, green, and blue bands according to the desired color pattern. The printed silver thin-film dots were molded by the underlying nanostructured surface into structural color pixels.…”

“…For example, when printing a big color pattern, alignment can be lost in some subregions due to inhomogeneous warping of the polymer substrate surface. Misalignment between the printed ink pattern and the pixel bands can cause wrong colors, referred to as “color leaking” . One solution in terms of equipment that is currently under development is a smart printing head that can optically detect pixel bands in real time and dynamically compensate alignment errors in all subregions.…”

Inkjet printed nanomaterial based flexible radio frequency identification (RFID) tag sensors for the internet of nano things

“…131 Inkjet printing will be a low-cost tool for rapid manufacturing of exible electronic devices. 132,133 Various types of conducting inks have been used for the inkjet printing process, including photonic crystals, 134 metal NPs, [135][136][137][138][139][140][141][142] graphene, [143][144][145][146][147][148][149] and polymers. 150,151 Li et al 127 fabricated metal oxide thin-lm transistors (MO-TFTs) by the inkjet printing method without using photolithography.…”